低水头枢纽泄流曲线率定方法与效果研究OA

[Objective]Under changing environmental factors such as sediment deposition,riverbed incision,and backwater effects induced by cascade reservoir impoundments,low-head hydraulic hubs in plain river basins often face the challenge that the design discharge curves of sluice structures do not match actual scheduling operation.To address the issues of low accuracy in the design discharge curves of low-head hydraulic hubs,this study,based on the analysis of the causes of discharge curve discrepancies,proposes a calibration method for discharge curves of sluice gates and demonstrates its performance through an engineering case study.[Methods]Taking a navigation and hydropower hub in the middle reaches of the Ganjiang River as an example,field measurements of discharge were conducted for sluice gates using a moving-vessel ADCP(Acoustic Doppler Current Profiler)measurement technique.The prototype observation results were used to calibrate empirical coefficients of hydraulic formulas and to validate the accuracy of a three-dimensional CFD(Computational Fluid Dynamics)numerical model.Under free-flow operation conditions of the sluice gates,the validated three-dimensional numerical model was employed to cal-culate discharge capacities of the sluice gates.The simulation results were further used to calibrate empirical coeffi-cients in hydraulic formulas,enabling the calculation of sluice-gate discharge under different combinations of up-stream and downstream water levels.[Results]The N-H-Q curve interpolation method provided high accuracy in calculating power-generation reference discharge and could be used to analyze the respective proportions of power-generation discharge and spilled discharge in the total outbound flow of the hub.When the sluice gate was partially opened to 0.5 m,the flow pattern downstream of the gate was submerged.When the gate was partially opened to 1.5 m,the flow transitioned to a free-flow pattern.Under the same conditions,the flow patterns through the sluice gate openings obtained from the three-dimensional CFD numerical simulation were consistent with field observations.Discharge values calculated using hydraulic formulas and three-dimensional CFD calculations agreed well with measured data,with a maximum deviation of less than 5％and an average deviation of approximately 1％.Consider-ing variations in upstream and downstream water levels of the hub and the operational range of sluice gate openings,a family of calibrated discharge curves for partially opened gates was calculated.When the gate was fully open for free discharge,different submergence coefficient calculation methods were required to determine the discharge de-pending on the degree of downstream submergence.[Conclusion]By integrating hydraulic calculation,prototype observation,and three-dimensional numerical simulation,a family of discharge curves under both controlled and free-flow operations of sluice gates is developed,adaptable to changing field boundary conditions and unaffected by time-varying environmental factors such as inflow magnitude,downstream backwater effects,or unsteady water level-discharge relationships.The calibrated discharge curves deviate from the measured data by less than 5％and can be used for practical application in hub scheduling and operation.